An argument between neighbors that turned deadly this weekend. A dispute abo overgrown trees. The neighbor arrested in the killing says he fired in self-defe self-defense. Abbie boudreau that has the... See More
An argument between neighbors that turned deadly this weekend. A dispute abo overgrown trees. The neighbor arrested in the killing says he fired in self-defe self-defense. Abbie boudreau that has the story. Reporter: A neighborly dispute over tree-trimming gone tragically wrong. Overnight, the man who shot him is calling it self-defense. Listen to this jailhouse interview with a chilling con vegs. He took two or three steps toward me and then I -- I -- shot him in the head. Reporter:61-year-old michael vilkin admits to killing his neighbor, humanitarian and film maker john upton. After a year-long argue about these bushes tied withing their property. He came to me, threatening, and pulled a at me. Reporter: Upton, a documentary film mark profiled by abc news in 1993 had dedicated much of his life to helping romanian orphans to finding homes. However they want me to do it, I'll do it. For god's sake, let me help these kids. Reporter: Vilkin's wife seen frantically here at the crime scene admits that police were called to resolve a dispute between the two men a week before the murder. Vilkin says his neighbor had an angry side. When upton confronted him with ta gun, he said he shot him. Police will not comment on where he was or was not brandishing a gun. His family left to wonder why this ended in bloodshed. We're just dumbfound like, what in the world happened? En mean it's just unbelievable. Reporter: For "good morning america," abbie boudreau, abc news, los angeles.
This transcript has been automatically generated and may not be 100% accurate.